Engines may include turbochargers and may use active control of the turbocharger, such as via a wastegate, intake throttle, a compressor bypass, etc., to increase efficiency of engine performance and thus vehicle driveability. In some vehicle applications, excess heat from the engine, e.g., in the form of hot air, may be used to heat various vehicle components, e.g., to heat the cabin of the vehicle, assist in throttle de-icing, and provide heat to humidity management systems, deliver heat to a window defroster, assist in accelerated engine warm-up, and provide heat to other vehicle and engine components.
However, during cold engine conditions when a temperature of the engine is less than a threshold temperature, e.g., during cold start conditions before the engine is sufficiently warmed up, excess engine heat may not be available to provide heated air to vehicle and engine components. In some approaches, heating elements, e.g., electric heaters, may be employed to assist in providing heat while the engine warms up. However, such approaches may reduce engine efficiency, e.g., may reduce fuel economy, since such heating elements consume additional energy during operation.
Further, during certain boosted engine operating conditions, pressure/flow in a turbocharger system may cause the turbocharger to surge potentially degrading turbocharger components and reducing vehicle performance. For example, a compressor may surge due to low air flow conditions with high pressure, e.g., when an intake throttle is closed or partially open. For example, such a surge event may occur after a driver tip-out event where a reduced amount of boost is requested for engine operation.
The inventors herein have recognized the above-described issues and, in one example approach, a method for a vehicle with a turbocharged engine is provided. The method comprises during a cold start condition, e.g., when an engine temperature is less than a threshold temperature or within a threshold of ambient temperature, diverting a portion of compressed air from downstream a compressor to a heat exchanger, and heating vehicle components via the heat exchanger. The method may further comprise, in response to a surge condition when the engine temperature is greater than the threshold temperature, diverting a portion of compressed air from downstream the compressor to the heat exchanger.
For example, an additional throttle and take-off conduit may be included between an intake manifold and a compressor in a turbocharged engine so that high pressure heated air can be delivered to a heat exchanger to provide heat to heat consuming vehicle and engine components, even during cold engine conditions. Further, such an additional throttle may be used to divert a portion of compressed air away from the intake manifold of the engine so that the compressor can flow additional air without the air being inducted by the engine in order to reduce surge.
In this way, heated air may be provided to various engine and vehicle components even during cold start conditions, e.g., while the engine temperature is less than a threshold engine temperature, without relying on an additional heating elements, e.g., electric heaters, which consume additional energy. In this way, engine efficiency may be increased while providing a faster source of excess heat during cold conditions. Further, this additional throttle may be used to provide greater control over turbocharger operation, e.g., to reduce surge events and to meet boost requests during engine operation.
It should be understood that the summary above is provided to introduce in simplified form a selection of concepts that are further described in the detailed description. It is not meant to identify key or essential features of the claimed subject matter, the scope of which is defined uniquely by the claims that follow the detailed description. Furthermore, the claimed subject matter is not limited to implementations that solve any disadvantages noted above or in any part of this disclosure.